Two-stroke-cycle internal-combustion engine



March 20, 1928.

C. LAW

TWO-STROKE CYCLE INTERNAL COMBUSTION ENGINE Filed Sept. 22. 1927 2 Sheets-Sheet 1 March 20, 1928.

c. LAW

TWO-STROKE CYCLE INTERNAL COMBUSTION ENGINE 2 Sheets-J-Shee;

F' ed Sept. 22. 1-927 Patented Mar. 20, 1928.

UNITED STATES.

PA OFF-ICE;

CECIL LAW, 01 GOLDERS GREEN, ENGLAND;

Application filed- September 22, 1927, Serial No. 221,203, and in Great Britain July 1-9, 1.826.

This invention has reference to two stroke cycle internal combustion engines of the kind wherein pairs of axially aligned pistons are disposed on opposite sides of a common combustion space in the cylinder and are adapted during portions of each cycle of working to move in the said direction and during the other portions to move in 0p.- posite directions. In a previously proposed construction of engine of this character the pistons are adapted to compress the scavenging air and combustible mixture prior to the introduction of the same into the combustion space. The primary object of the invention is to provide improvements whereby the construction is ,materially simplified by the elimination of valves which have heretofore been considered necessary for the proper running ofthe engine.

According to this invention, the cylinder is provided with two sets of inlet transfer and exhaust ports respectively controlled by a pair of pistons capable of operating as hereinbefore referred to, each piston being adapted to control its respective set of ports in the cylinder. The pistons are preferably arranged to compress scavenging air and combustible mixture in casings prior to the introduction of'the air and mixture into the combustion space, the casings being connected to the cylinder and the passage of the compressed air and mixture to the combustion space being controlled by the respective pistons. Preferably the pistons arearranged in conjunction with cranks or the equivalents thereof so set relatively to the firing of the charge that one crank orthe equivalent thereof is set 45 in advance and the other 45 to the rear of the dead centre positions.

In order that the said invention may be clearly understood and readily carried into effect, the same will now be fully described, by way of example, with reference to the accompanying drawings, in which Figure 1 is a sectional elevation illustrating an arrangement of one pair of pistons connected to a pair of geared crank shafts.

Figure 2 is a sectional elevation of two pairs of pistons connected to the same shaft.

Referring to the construction shewn in Figure 1, it will be seen that the engine consists in effect of two single-cylinder two stroke cycle engines bolted end to end with their crank cases outermost and their pie-- tons each adapted to control the ports in the end of the power stroke.

their respective cylinders. The crank shafts each other that onev crank dis 270 in advance of the other crank e, the crank shafts being caused to rotate in the same direction in this. relationship by the said chain gearing 0 and c, .although other suitable, forms of gearing maybe used for the purpose. 111 thus arranging the cranks, they are so disposed relatively to each other in the approximate firing position, that the crank dais 4:5 in advance of the, inner dead centre position and the other crank e is 15 tothe rear thereof, the crank at being in its most effective angular position for transmitting to its shaft a the full effort exerted b-ythe fired charge, while the, other crank e is advancing to this effective position for continuing the fullelfectof the expanding gases. .Owing to this disposition of the cranks d and eofthe pair of'associated-pistons fand f, it will be seen thatafter the moment of ignition both pistons will travelin the same direction, but the lower will be accelerating while the upper one will be decelerating. This continues for 45, after which the top piston changes its direction, the bottom piston continuing downwards to ncover its respective ports. this means progressive expansionof the gases is obtained right to Furthermore the crank (if, being in its most effective position at the moment of ignition, serves through the chain gearing to move the other I crankme past its dead center position during the expansion of the fired charge. The pistons f and f are connectedto the cranks d and e bythe piston rods g and g and are enclosed in the cylinder h which is approxi matelytwice the normal length of that provided for a single piston engine. Each' end ofthe cylinder is closed by a crank casing j and j and into the latter the air and mixture are respectively introduced and compressed during the reciprocatio-ns ofzthe pistons. The compressed air and mixture pass by conduits 7c and is into the cylinder when the ports and 10 are uncovered by the pistons f and f. The inlet port I for the air and the inlet port m, for the mixture are respectively controlled by the pistons f and f, the air and mixture being admitted when the pistons are near the ends of. their inner strokes. When the pistons f and f are near the outer limits of their strokes they uncover the ports 70 and 70 respectively as well as the exhaust ports n and the compressed air and mixture in the crank casings pass through the conduits la and 7c and sweep the waste products of combustion from the cylinder through the exhaust ports a. 0 designates a recess in the cylinder for a sparking plug; With the arrangement of inlet ports shewn in Figure 1, it is feasible to provide means for supplying mixture through the air inlet port Z as well as the mixture inlet port m, one form of means to this end comprising a valve controlled fuel supply pipe or jet attached to the air inlet pipe. The latterand the mixture inlet pipe are both provided With throttle valves and to'the supply side of the throttle valve of the air inlet pipe is fitted the said fuel sup ply pipe or jet. With such an arrangement it is possible to supercharge the engine when required.

In an alternative construction the shafts a and b may be geared together to rotate in opposite directions and in this arrangement the cranks (Z and 6 connected with one pair of pistons are so positioned relatively to each other that at the firing of the charge, one crank is about 75 in advance of its inner dead centre position, whilethe other crank is about 15 to the rear ofits inner dead centre position. Following the firing of the charge the latter crank is moved past its inner dead centre by the effort exerted through the first mentioned crank which is at a much greater angular distance from its '0 and'a and a single shaft p, the latter being disposed between the cylinders h and it? and being fitted with a flywheel g. The swash plates at" and a are pivotally connected at their outer ends to the respective pistons and operate in conjunction with circular cams a and a provided on sleeves r secured to the shaft p. The sleeves r are disposed in casings 7' and 7' which are respectively equivalent to the crank casings j and y" of the construction described with reference to Figure 1, and are adapted for the introduction of air and mixture by inlet ports Z and m. The casings 7' and 7' are placed in communication with the outer ends of the cylinders when the pistons are near the inner ends of their strokes, as shewn in the upper left hand portion of Figure 2. The air and mixture thus admitted into the cylinders are respectively compressed dur ingthe outward strokes of the corresponding pistons, and near the outer ends of such strokes pass through the ports k and k and conduits 7c and into the cylinders be tween the pairs of pistons for the purpose of expelling the waste products of combustion and recharging the cylinders with a .combustible mixture capable of being fired by sparking plugs (not shewn) but adapted to be disposed in the recesses 0. Thewaste products of combustion are expelled through ports (not shewn) but provided in the cylinders but approximately opposite to the ports 70 and [e as in the construction described with reference .to Figure 1.

lVhat I claim and desire to secure by Letters Patent of the United States is 1. A two-stroke-cycle internal combustion thereof, a pair of axially aligned pistons disposed in saidcylinder, one in each half thereof, said pistons being each adapted to control the ports in their respective half of the cylinder, and an operative connection between said pistons adapted to correlate their movement and cause the opening and closing of the ports inone half of said cylinder at a different time during'the operating cycle than the ports in the other half of said cylinder.

3. A two-stroke-cycle internal combustion ill) engine comprising a cylinder having an inlet and an exhaust port in each half thereof, and a pair of operatively interconnected axially aligned pistons disposed in said cylinder, one in each half thereof, said pistons being each adapted to control the ports in their respective half of the cylinder and to pass beyond the inner dead center position into the other half of the cylinder.

at. A twostroke-oycle internal combustion engine comprising a cylinder having an inlet engine comprising a cylinder having an inlet and an exhaust port in each half thereof, a pair of axially aligned pistons disposed in said cylinder, one in each half thereof, said pistons being each adapted to control the ports in their respective half of the cylinder, an operating shaft arranged at one end of said cylinder, mechanism including a crank set 45 in advance of the inner dead center position connecting one of said pistons to said shaft, a second operating shaft arranged at the other end of said cylinder, mechanism including a crank set 45 to the rear of said inner dead center position connecting said other piston to said second named shaft, and mechanism connecting said shafts.

6. A two-stroke-cycle internal combustion engine comprising a cylinder having an inlet and an exhaust port in each half thereof, a pair of axially aligned pistons disposed in said cylinder one in each half thereof, said pistons being each adapted to control the ports in their respective half of the cylinder, an operating shaft arranged at each end of said cylinder, mechanism connecting said shafts, and connections between said shafts and said pistons adapted to correlate the said cylinder, one in each half thereof, said pistons being each adapted to controlthe ports in their respective half of the cylinder, a crank case arranged at each end of said cylinder and provided with a transfer conduit communicating with said inlet ports, a

crank shaft disposed in each crank case, the

crank of-one shaft bein set at an angle of substantially 90 to the crank of the other shaft, mechanism connecting said shafts, and

connections between said shafts and said.

pistons adapted to correlate the movement of said pistons and cause the'opening and closing of the ports in one half of said cylinder at a different time during the oper ating cycle than the ports in'theother half of said cylinder.

, CECIL LAW. 

